Erythromycin A is the major analogue of a complex of closely related analogues produced by Saccharopolyspora erythraea to become the first macrocyclic lactone antibiotic. Metabolite complexes are common in microbial fermentations and provide an ecological advantage to the microbe in a hostile and bio-diverse environment via differing physico-chemical properties and spectra of action. The Erythromycin Metabolite Set includes the major co-metabolite analogues of erythromycin described in the literature and provides a tool for understanding the pharmacological potential in nature’s design of the erythromycin family. | 1. Erythromycin A - (CAS# 114-07-8) - Molecular Formula: C37H67NO13 – Molecular Weight: 733.9 | 2. N-Demethylerythromycin A - (CAS# 992-62-1) - Molecular Formula: C36H65NO13 - Molecular Weight: 719.9 | 3. Erythromycin A N-oxide - (CAS# 992-65-4) - Molecular Formula: C37H67NO14 - Molecular Weight: 749.9 | 4. Erythromycin B - (CAS# 527-75-3) - Molecular Formula: C37H67NO12 - Molecular Weight: 717.9 | 5. Erythromycin C - (CAS# 1675-02-1) - Molecular Formula: C36H65NO13 - Molecular Weight: 719.9